Emerging technologies that integrate computational algorithms and physical components in a hybridized engineered system are referred to as cyber-physical systems (CPSs). In a CPS, there may be a network of hardware and software “cyber” components that monitor, modify, or enact behavior within a physical process or component. Suggested applications of CPSs have included autonomous vehicles, “smart” infrastructure, medical monitoring, or advanced manufacturing, among others. In a typical system, a network of components may include sensing, actuating, computing, and communication capabilities that are seamlessly integrated in a physical system. The tight integration of cyber with physical components, however, increases the security vulnerabilities of the physical components, for example, an autonomous car being susceptible to remote control through an attack by a computer hacker. It is therefore important for a system and method of authentication of users in a CPS-enabled environment.
There are a number of methods currently employed for authenticating users of a computer system, but they have a number of disadvantages. The complexity of CPSs and their components have introduced new difficulties to security and privacy protection that are not encountered in more traditional computing devices. Furthermore, the nature of CPS functionality and use across a variety of environments and applications may increase potential motivators or sources of security threats. It may be important to employ hierarchical security architectures for certain applications. Hierarchical architectures are important to offer the flexibility to increase or decrease the level of security of CPSs depending on a threat level. Within a highly secure environment it may be desirable to simplify the access control, whereas in the case of an unknown or unsafe environment, additional protections may be needed. Current hierarchical architectures that can implement low-security backdoor capability are complicated to implement and could create easy entry points to a hacker. It would be beneficial to have a security architecture that more efficiently and reliably provides variable levels of security for accessing a cyber physical system.